I decided to "blueprint" the oil pump today. Not much to it other than verifying that there is no crap inside the casting.
I'm glad I took a look. This is a brand-new Melling M54DS oil pump. Inside, all of the machined surfaces were incredibly sharp and I found tiny metal burrs and little shards that were just sitting there, waiting to get pumped in to engine. NEVER trust a new pump without looking inside it first.
Here is the housing once I pulled the gears out. See how sharp the edges are?
Now take a closer look and you can see a metal splinter leftover from the machining process that was under the gear, as well as burrs on the edges of the machined passages.
I spent a while with a Dremel tool and some fine sandpaper smoothing all the internal edges. I also used a 1/2" drill bit to open up the feed hole that mounts to the block to it's correct 1/2" size. It was rough cast from two halves and they were not matched up correctly. I then washed and scrubbed and brushed the housing out in hot water and soap.
Here is the housing after the edges were smoothed and before washing:
And the final pump reassembled. I packed it with grease so it will prime instantly when the times comes.
